For decades, medical professionals, such as dentists, have routinely used X-ray radiographs for disease detection, diagnostic decision making and treatment monitoring. X-rays are emitted by an X-ray generator, pass through the structures of interest such as teeth, bone and soft tissues of the head and jaws, and are captured by an appropriate receptor. The traditional receptor, X-ray photographic film, is still the most widely used. In such film-based systems, the latent image is produced on the film through activation of silver halide crystals which are then rendered visible by processing the exposed film in chemical solutions. Such film processing takes several minutes when a series of X-ray films are exposed on the patient. If, after developing, the images are discovered to be unusable due to film placement or image geometry errors, a new series of films need to be exposed. This increases the patient x-ray dose.
Recently, systems have been introduced for electronic acquisition of dental X-ray information through the use of charge coupled device (CCD) image receptors. Current CCD receptors for oral, intraoral and maxillofacial imaging tasks use either radiation-hardened CCD arrays (Regam SensAray, Sundvaal, Sweden) or CCD arrays coupled to a scintillator such as a rare-earth X-ray screen material (Trophy Radiologie, Vincennes, France). The largest area array currently used in dental imaging is now approximately 760 pixels by 524 pixels (Schick Technologies, New York), which results in a resolution of about 10 line pairs/mm.
Imaging with a CCD receptor requires approximately 70-80% less exposure time than imaging with X-ray film. Thus, the patient X-ray dose is lessened. However, most current X-ray generators were designed for use with film receptors; consequently, they produce too much X-ray radiation, overloading the CCD receptor and increasing the patient absorbed X-ray dose.
Another problem with current X-ray generators is that they are large and heavy, thereby requiring that they be installed in a fixed location. For dental applications, the X-ray generator is typically fixedly mounted to the distal end of an articulating arm which is in turn mounted to the wall of the dental operatory. The weight of the tubehead often requires the placement of additional support in the wall where the unit is mounted in order to support the tubehead at its maximum length from the wall. Because a dental office normally includes several operatories, the provision of X-ray imaging capability to each of the operatories requires a substantial investment since multiple X-ray units much be purchased.
There is, therefore, a need for an X-ray device that will lessen the patient X-ray dose. There is also a need for an X-ray device that can easily be used in several different operatories in order to reduce duplication of equipment within the dental office. The present invention is directed toward meeting these needs.